We report the study of photoluminescence ( PL) spectroscopy in InAsN epilayers grown by molecular beam epitaxy. All the samples exhibit intense PL emission which persists up to room temperature. Low temperature PL spectra demonstrate double-peak emissions. The dependences of the PL spectra on temperature, laser excitation power and nitrogen composition were investigated. We identified that the short wavelength and long wavelength emissions originate from the band-band transition and the localized states-valence band transition, respectively. The direct observation of the band-band transition implies the high quality of the materials, and a band-gap energy reduction of similar to 63 meV at 4 K with 1% nitrogen incorporation was deduced.